What's the best treatment to get rid of cholecystitis?

Cholecystectomy. The treatment for inflammation of the gallbladder is to surgically remove it. During the initial phase, treatment includes antibiotics and no oral intake until the gallbladder "cools off" for a day or two, then it is removed. If the gallbladder has swollen to the point of rupture, it is removed immediately. Gallbladder is not an essential organ.
Depends. You need to know the cause of the cholecystitis, as there are many. Need more history. If it is due to cholelithiasis (gallstones), then a visit to a good general surgeon may be beneficial.